Temperature conditioning of sugar bearing material



Sept. 2, 1941. c. A. OLCOTT 2,254,390

TEMPERATURE CONDITIONING OF SUGAR BEARING MATERIAL Filed July 8, 1939lNl/ENTOR C. A. OLCOTT BY MW A T TORNEY Patented Sept. 2, 1941 UNITEDSTATE-SPATENT OFFICE TEMPERATURE CONDITIONING SUGAR BEARING MATERIALCharlgA om, West Milford, N. 1. Application my a, 1939, Serial no.283,438'

13 Claims. (01. 121-19) This invention relates to-the extraction ofsugar from sugar hearing material and more particularly to apparatus fortemperature conditioning of sugar bearing material.

An object of this invention is to obtain the optimum yield of sugar fromsugar bearing material commensurate with eiiiciency and economy.

Another object of this invention is to obtain a uniform temperaturethroughout a mass'of sugar bearing material.

A more particular object of this invention is to insure that everycharge of sugar bearing material introduced into a centrifugal is heateduniformly and that the temperature of. the material is accuratelycontrolled.

In the preparation of massecuite or other sugar bearing material for theseparation of sugar therefrom in centrifugal machines, the temperatureof the massecuite is raised to a point at which the mas'secuite becomesmore fluid and the mother liquor separates easily from the sugargrainsin the centrifugals. However, the increase in temperature of themassecuite is limited to insure that the temperature does not rise to apoint at which the sugar grains redissolve. The heating takes place in ahot mingler or mixer, which comprises an elongated tank containing aheated stirrer. Disposed in a row below the mixer are the centrifugals,each immediately beneath a respective discharge spout that leads fromthe bottom of the mixer tank and through which the heated magma,massecuite or other sugar bearing material is from time to timedischarged for centrifuging.

Although it is intended that the stirrer shall raise the temperature ofthe entire mass of cold magma supplied to the mixer uniformly to apredetermined optimum value so that all of the magma supplied to thecentrifugals shall likewise be uniformly of that same temperature, it isfound in actual practice that this desired result is only imperfectlyachieved. More specifically, it is found that the temperature of themagma delivered from any one discharge spout may vary to anobjectionable extent not only throughout the day but during a singleloading.

trifugals, and fixed for magma of a given temperature! and viscosity.The second ill effect arises from the non-uniformity of temperaturethroughout the charge of magma in a given centrifugal. In the latter themother liquor is thrown from the spinning basket at a rate depending onits viscosity, and if the temperature is non-uniform it leaves differentparts of the basket'at different rates; Such irregularities in the rateof drainage from difierent parts of the basket unbalances it anddangerous gyrations may occur. The tendency toward centrifugals ofhigher rotational velocities aggravates the condition described andpresents an increasingly serious hazard for the sugar refiner.

I attribute the non-uniformity of magma discharge temperature obtainingwith hot minglers as heretofore employed in part to the fact that magmais discharged from the tank at points widely spaced along its length andat irregular time intervals, whereas the tank contains cold I magmanewly introduced, magma at the optimum temperature, and partially heatedmagma at various intermediate temperatures. In certain minglers of theprior art it is possible, in fact, for some of the cold magma to moverather directly from the point where it is introduced to a dischargespout that may be open at the'time. I I

In accordance with one of the principal features of the presentinvention the process of heating the magma in preparation forcentrifuging is substantially isolated from the process of dischargingit to the several centrifugals insofar as concerns the efiect ofdischarge on uniformity of heating. Another feature is that magma cannotreach a discharge spout unless and until it has passed completelythrough the heating phase.

Another principal feature of the invention provides for accurate controlof the heat sup- I plied to the magma in relation to .its' dischargetemperature.

Heretofore, considerable difliculty has been experienced in ascertainingthe average temperature of the mass of material in the mixer andcorresponding difficulty in making the necessary continuous adjustmentsin the amount of of its associated centrifugal, and that also at anygiven time the magma temperature varies from one spout to another. Thesevariations are highly undesirable for at least two reasons. First, thequality and yield of sugar is impaired inasmuch as the centrifugingcycle, in accordance with modern practice, is automatically controlled,of the same duration for all of the cenheat supplied to it to compensatefor changing conditions such as variations in the entering magmatemperature and variations in the rate of discharge of magma from themixer. In accordance with a feature of the present invention the slowlymoving mass of magma in the mixer is converted into a fairly fine streamof normally correspondingly higher velocity, and in In accordance with apreferred embodiment of the invention incorporating the several featureshereinbefore described as well as others that will appear hereinafter, atank is provided that is separated longitudinally into two compartmentswhich may be approximately described and conveniently referred to asupper and lower compartments. The tank, preferably, overlies-,.,a,battery of centrifugals and each centrifugal may be charged from time totime as required with sugar bearing material through a respective spoutfrom the lower compartment of the tank. The ,cold sugar bearing materialis introduced .into the upper compartment of the tank, where it isheated toa uniform temperature and it then passes to the lowercompartment. The

means provided for heating the material in the upper compartmentcomprises preferably a hollow coil through which a heated fluid mediumpasses. Preferably, the material is poured into the upper compartment atthe point of the coil at which the fluid medium is highest intemperature, While the material passes to the lower compartment at apoint where the temperature of the coil is lowest. With thisarrangement, as the sugar bearing material passes through the uppercompartment, the heat energy transferred from the fluid medium to thematerial becomes progressively less until at the passage of the materialfrom the upper to the lower compartment, substantially to heat energy isimparted to the material. A thermostat or equivalent device is providedto regulate the rate of heat transfer from the heating means to thesugar bearing material in the upper compartment so that the heatsupplied will constantly be just suflicient to maintain the temperatureof the material leaving that compartment at the desired optimum valuedespite variations in the rate of flow of the material and in itsinitial temperature.

Whereas the material moves fairly slowly through the heatingcompartment, it is constrained at the point-of its discharge from theheating compartment to the lower compartment to move comparativelyrapidlyin a stream of much restricted cross section. In accordance witha principal feature of the invention a thermo-responsive device isplaced in this rapidly moving stream. and. it is the response of thisdevice that is utilized to control the rate at which heat is suppliedfrom the coil to the sugar hearing material. This arrangement has theoutstanding advantage in that it truly reflects the temperature of thewhole mass of sugar'bearing material delivered to the lower compartment.

The lower compartment is thoroughly heat insulated or otherwise arrangedso that the sugar bearing material delivered to it, which on delivery isat the optimum temperature for centriiuging, undergoes no appreciablechange in.

temperature. No'materlal enters the lower compartment except that whichhas been subjected to the,complete and continuously controlled uniformheat processing in the upper compartment, hence only material that is atthe optimum temperature for centrifuging has possible access to A morecomprehensive understanding of thisinvention is obtained by reference tothe accompanying drawing in' which: Fig. 1' is a front elevation partlyin section of I an apparatus for effecting a-uniform temperature of asugar bearing material prior to centrifuging in accordance with thisinvention.

. Fig. 3 shows an alternate form of a portion of apparatus along thelines 3-3 of the system shown in Fig. 1.

In Figs. 1 and 2. sugar bearing material passes from one or morecrystallizers l0 through an outlet controlled by a valve I2 to a scrollconveyor. taining a scroll conveying member I rotated througha pair ofgears l5 and I6 by means of a suitable source of power not shown. Theconveying member it rotates at such a speed and in such a manner as topass the'sugar bearing material introduced into the trough to a spoutII.

From the spout H, the sugar bearing material passes into an uppercompartment or elongatedchannel IQ of a. mixer or tank for supplying thematerial to a plurality of centrifugals 20. The mixer or tank comprises,in addition to the upper compartment or chamber IS, a lower compartment2|. The upper compartment I! has a semi-circular bottom, and concentricwith this bottom is located a heater stirring coil 22. The heaterstirring coil 22 is rotated'through gears 23 and 24 by a source ofpower'not shown and is supported by bearings 25 and 26, both of whichare fixedly attached to the lower compartment 2|, and by a bearing 21held rigidly in a barrier 38 of the upper compartment l9. The'coil 22 issupplied with heated fluid medium such as hot water from a tank 28through a valve 29, a circulating pump 30, a pipe or conduit 3|, and astufling box 32. After passage through the coil 22, the fluid medium isreturned to the tank 28 through a. stuffing box 23 and a pipe or conduit34. Located in the return line is a thermostatic bulb 35 which controls,through a mechanical linkage 36, the valve 29. The thermostat 35 may besimilar to that shown in the copending application of applicant, SerialNo. 236,659, filed October 24, 1938, or any other well known device. Thevalve 29 is adjusted to close at any desired predetermined temperatureand is constructed so as to close partially to decrease the flow offluid medium through the coil 22 as the predetermined temperature isapproached. In the operation of the mixer in modern practise, it isdesirable to have the valve set to close when the temperature of thefluid medium in the return line is between to degrees Fahrenheit. Thefluid medium in the tank 28 is heated by means of steam supplied througha coil 31. Thermostatic control of the steam may be effected to insurethat the temiii The conveyor comprises a trough l3 con- 7 the lowercompartment 2|. The upper compartment l9 terminates in a barrier 33which aflords a passageway for the material from the upper compartmentH! to the lower compartment 2|. The side or barrier 38 of the uppercompartment l9 over which the sugar bearing material flows into thelower compartment 2| is of lesser height than the other sides of theupper compartment. The height of the barrier 38 is, of course,sufllciently great to insure that the heater stirring coil 22 iscompletely covered by the material in the upper compartment before thematerial passes to the lower compartment. 7 The heater stirring coil 22may be of any well known type of construction and its particular form isof no great importance in a short mixer. In a long mixer serving manycentrifugals, however, it is preferable that the convolutions of thecoil be wound in the form of a spiral so that by the rotation of thecoil, the material may be conveyed toward the barrier 38. The spout llof the scroll conveyor is located to deposit the sugar bearing materialin the upper compartment l9 so that the relatively cold sugar bearingmaterial flowing from the spout I'I comes in contact with the hottestportion of the heater stirring coil 22. In the embodiment illustrated,this position would, be the point of the coil nearest the source ofsupply of the fluid medium from the tank 28. The material is thenconveyed to the barrier 38 by means of the rotation of the coil 22 andpasses over the barrier to the lower compartment 2|.

Means are provided in the lower compartment 2| for agitating the sugarbearing material therein to prevent the settling of the grains of sugarin the sugar bearing material. In the specific embodiment illustrated,these means comprise a plurality of paddles 39 fixedly attached to ashaft The bear- 40 supported by bearings 4| and 42. ings 4| and 42 arefixedly attached to the lower compartment 2|. The shaft 40 is rotatedthrough gears 43 and 24 by a source of power not shown. While anysuitable stirring means may be employed in the lower compartment, it isimportant that the stirring means should not be heated. since anyheating element in the compartment would destroy the uniformity oftemlizers in order to render the material suiliclently mobile to-permitits ready transportation by means of the scroll member to the spout H.The relatively cold sugar bearing material flows through the spout l1and comes into physical contact with the hottest portion of the heaterstirring coil 22. The heater stirring coil 22 impartsheat energy to thematerial and, due to the rotation of the coil 22, the material movestoward the barrier 38. increases progressively in temperature until,upon its passage to the lower compartment 2|, it has I attained thedesired uniform temperature reperature throughout the mass containedtherein, which condition would, in turn, result in irregularities in thetemperature of the material in the centrifugal basket. In order toprevent cooling of the material contained in the lower compartment 2|,the compartment is preferably insulated by insulation 44 or by a waterjacket. A cover 45 composed of a heat insulating material is alsoutilized to prevent the dissipation of heat energy from the materialcontained in the tank 2|.

The ,sugar bearing material in the lower compartment 2| of the mixer iswithdrawn fromtime to time as required to pass into the centrifugalsthrough a plurality of spouts 46, each spout being controlled by one ofa plurality of valves 41. Each of the spouts overlies a centrifugalmachine 20. When required, the desired amount of material is withdrawnfrom the lower compartment 2| of the mixer through the-spout 46 to thecentrifugal 20.

In operation, the sugar bearing material is brought, in accordance withthe usual practise, to a low temperature by means of coils or naturalradiation in the crystallizers Hi. If the material has been boiled to avery high density, it may be heated slightly by the coils, if any, inthe crystalchamber.

quired for processing in the centrifugal machines. The coil 22 issupplied with hot water or other fluid medium at a temperature ofapproximately 210 degrees Fahrenheit. If the temperature of the fluidmedium exceeds that for which the thermostatic bulb is adjusted, thevalve 29 closes to prevent the passage of hot water from the tank 28 tothe coil 22. As a result of this arrangement,-the temperature of thematerial flowing over the barrier 38 cannot exceed that for which thethermostatic bulb 35 is adjusted. If it did, the material would not coolthe water or other fluid medium to a temperature suflicien-tly low topermit the valve 29 to be opened; Consequently, there is no circulatidnof water after the material has attained the predetermined temperaturefor which the thermostatic bulb 35 is adjusted. As heretofore noted, thevalve 29 is constructed so that, as the predetermined temperature isapproached, the valve 29 partially closes. With this construction of thevalve, the flow of the fluid medium through the coil 22 is markedlydecreased as the predetermined temperature is approached, whereby lessheat energy is imparted to the sugar bearing material and, in general,the flow of the medium through the coil 22 is increased or decreaseddependent upon the heat energy required to increase the sugar bearingmaterial to the desired temperature.

The material passed over the' barrier 38 from the upper compartment IQof the mixer into the lower compartment 2| is, as a consequence ofconditioning in the upper compartment, of a uniform temperature. Theunheated paddles 39 in the lower chamber 2| prevent the settling of thegrains of sugar in the Inaterial'contained in the The material containedin the chamber 2| iswithdrawn from time to time through spouts 46controlled by gate valves 41 to supply therespective centrifugals 20 asrequired.

A gate 48 controlled by a handle 49 is located at the bottom ofthe'upper compartment l9, preferably at a point in proximity to thebarrier 38. This gate may be opened to drain the upper com- .partment atany time it is desired to liquidate the that disclosed in the copendingapplication of applicant, Serial No. 268,004, filed April 15, 1939, maybe provided for preventing the fluid medium flowing through the coil 22from passing by leakage into the sugar bearing material contained in theupper compartment.

Instead of the temperature of the sugar bear- As it moves toward thebarrier, it

ing material flowing over the barrier 38 being controlled by means ofthe temperature of the water after passage through the coil 22, thetemperature of the material can be regulated by inserting a thermostaticbulb for the control of the valve 29 in the stream of material passingover the barrier 38. This arrangement is shown in Fig. 3 whichrepresents a fragmentary gportion of an alternate-form of the apparatus;shown in Fig. 1 along the lines. 3-3. A thermostatic device 50 of thebellows type, for example, is

positioned in the tank I! immediately adjacent to the barrier 38 so thatthe sugar bearing material passing over the barrier 38 comes in contactwith the device 50. The thermostatic device ill controls, by means ofmechanical linkages SI, 52, and 36, the valve 29, the linkage 52 beingheld by a pivot 53. The thermostatic device 50 is adjusted at thedesired predetermined temperature which is required of the materialprior to centrifuging. The modification of the invention including thefeature illustrated in Fig. 3 operates in the same manner as that shownin Fig. 1 and Fig. 2 except that the control of the fluid medium passingthrough the coil 22 is eflected directly by the temperature of thematerial passing over the barrier 38. When the temperature of thematerial passing over the barrier 38 is below the predetermined temperature for which the thermostatic device 581s ad- Justed, heated fluidmedium from the tank 28 passes through the coil 22. However, when thematerial attains the predetermined temperature,

the valve 29 closes to prevent the passage of the 1. In a system for thetemperature conditioning of sugar bearing material immediately prior tocentrifuging, a container including a first compartment and a secondcompartment, ingress means for introducing relatively cold sugar hearingmaterial into said first compartment, a passage through which thematerial in said first compartment flows into said second compartment,egress means for withdrawing said. material from said second compartmentand means in said first compartment for progressively increasing thetemperature of sugar bearing material introduced through said ingressmeans at a progressively slower rate as said material ap-- proaches saidegress means, said ingress means lower compartment only after completionof heating by said heating means, said heating means being the soledevice for substantially altering the temperature of the mass of sugarbearing material in said tank, and means for controlling the temperatureof the sugar bearing material passing from said upper compartment tosaid lower compartment. 7

3. In a system for the extraction of sugar from sugar bearing material,a mixer comprising an upper compartment for receiving relatively coldsugar bearing material, a lower compartment having a plurality of spaceddischarge parts, a point of ingress in said upper compartment, a pointof discharge in said upper compartment at which the material from saidupper compartment passes to said lower compartment, means in said uppercompartment for progressively heating and transporting said materialfrom said point of ingress to said point or discharge, means controlllngsaidheating means for maintaining a substantially constant temperatureof the material at said point of discharge, said heating meansbelng thesole device for effecting a substantial temperature change in the massof said material prior to centrifuging.

4. An apparatus for containing a sugar bearing material prior tocentrifuging comprising a tank overlying a centrifugal, an uppercompartment in said tank for receiving relatively cold sugar bearingmaterial, heating means in said upper compartment for heating saidmaterial, a lower compartment in said tank having a plurality ofseparate outlets for discharging sugar bearing material into acentrifugal, means for passing the sugar bearing material from saidupper compartment into said lower compartment after subjection to saidheating means, and means, responsive to the temperature of the sugarbearing material at the point of passage from said upper compartment tosaid lower compartment, for controlling the amount of heat energyimparted to the sugar bearing material in said upper compartment by saidheating means, said heatingmeans in said upper compartment being theonly means in either compartment capable of substantially modifying thetemperature of said material.

5. Apparatus for obtaining a limited temperature change in a mass ofsugar bearing material comprising a tank, an elongated channel in saidtank through which sugar bearing material passes, heating means in saidchannel for progressively heating said material as it passes throughsaid channel, a storage compartment in said tank into which the materialflows from said channel after it has passed through said channel, means,responsive to the temperature of and said passage being localized atspaced points along said first compartment.

2. An apparatus for containing a sugar bearing material prior tocentrifuging comprising a tank overlying a battery of centrifugals, anupper compartment in said tank for receiving relathe material at thepoint where it fiows from' said channel to said compartment, forcontrolling said heating means, and a plurality of discharge outletsfromsaid storage compartment for distributing the material therein.

6. Apparatus for efiecting a limited temperature change in a mass ofsugar bearing material comprising a tank having a first compartment anda second compartment, means for conveying the material from said firstcompartment to said second compartment, heating means in said firstcompartment for imparting heat energy to said material, said heatingmeans being the sole source of heat in said tank, means in said secondcompartment-for conserving the heat energy imparted to said material andagitating means in said second compartment for preventmeans for heatingsaid magma as it moves from said one point to the other, means forregulating thesettling of the grains in the sugar bearing material.

'I. A hot mingler for the temperature conditioning of magma or othersugar bearing mate-- rial prior to centrifuging comprising an elon- '5gated reservoir for containing said magma and adapted to maintain saidmagma without substantial change inheat content, a plurality of outletsspaced along the bottom of said reservoir ing the'rate of said heatingto maintain the discharge temperature of said magma substantiallyconstant, a second elongated compartment connected to receive the magmadischarged from said discharge point, a plurality of discharge spoutsalong said second compartment for discharging the said magma therein-toindividual for discharging said magma to respective cenfmjcentrifugalsas required. Said Second compa trifugals as desired, an elongated tanksuspended in said reservoir, a heat exchanger comprising a coilrotatably mounted lengthwise in said tank and means forcirculatingheating fluid through said coil from one end thereof to the other,

of said tank, said tank being so proportioned 29 that the said magma soconveyedflows over the said other end into said reservoir, athermoresponsive device immersed in the magma flowing over said otherend, and means controlled by said device for regulating the rate atwhich heat is supplied by said heat exchanger to said magma, saidcontrolled means operating to maintain the temperature of the magmaflowing from said tank substantially constant.

8. A hot mingler for the temperature conditioning of sugar magma or thelike comprising an elongated tank and means dividing said tanklongitudinally into two compartments, one of said compartments beingadapted to receive at one point along its length the magma to betemperature conditioned, means for conveying the said magma from saidone point to another point longitudinally spaced therefrom for dischargeintothe other of said compartments, means in said one compartment forheating the magma conveyed therethrough, means for regulating the heatsupplied by said heating means to maintain the said magma at asubstantially constant temperature at its said point of discharge, and aplurality of outlets spaced along said other 'compartment forcontrollably discharging the magma therein to respective associablecentrifugals, said other compartment being adapted to maintain the magmatherein at substantially the temperature at which it is admittedthereto.

9. A hot mingler for preparing sugar magma for centrifuging comprisingan elongated compartment having a single localized charging point and asingle localized discharge point spaced longitudinally of saidcompartment from said charging point, means adapted to move said magmafrom said charging point to said discharge point,

ment being so constructed and arranged that the magma therein ismaintained at substantially constant temperature.

10. The continuous process of hot mingling sugar magma or the like priorto centrifuging which comprises moving the magma in a slow stream oflarge cross-section area andsimu-l- ,taneously dry heating said magmawhile so moving, moving the said magma immediately after the said dryheating thereof in a relatively fine stream of correspondingly highvelocity, and continuously regulating the rate of said dry heating underthe control of the temperature of said relatively fine stream of magma.

11. A hotv mingler tank containing sugar magma or the like, means forheating the mass of magma in said tank, means for discharging.

through said coil from one endthereof to the other, said tank beingadapted to receive magma at one end and to discharge said magma at thevarying the efiective temperature of said coil inversely with thetemperature of the magma discharged.

13. A combination in accordance with claim 12 in which the said tank isso proportioned that the said magma flows over the end wall thereof atthe said point of discharge.

